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Transcript of Exercise 2 Full Presentation
EXERCISE 2TERNARY SYSTEMS
Andrew Nico S. Lozano
CHEM 112.1 2L
2nd Semester A.Y. 2009-2010
GIBBS PHASE RULE
Gibbs Phase Rule
formulated by J. Willard Gibbs of Yale University
A general expression for the number of intensive variables that have to be specified for a multiphase system at equilibrium
A rule for discussing phase diagrams; applicable for all phase diagrams
Gibbs Phase Rule
Basic formula:
2F C P Where:
F = degrees of freedom = number of variables that can be varied
C = Number of components in a system P = Number of phases 2 = means that temperature and pressure
are varied
Gibbs Phase Rule
If either temperature or pressure is held constant:
If both temperature and pressure are held constant:
1F C P
F C P
TERNARY SYSTEM
Ternary System
A system having three (3) components C = 3 Gibbs Phase Rule:
2
5
F C P
F P
Ternary System
Problem:Cannot be illustrated graphically, since there
are four (4) or more parameters that can be varied
Solution for this case:Keep the temperature and pressure
constant
Ternary System
By keeping temperature and pressure constant:
In any number of phases, one can already illustrate the system using what was called a Gibbs-Roozeboom Diagram
3
F C P
F P
GIBBS-ROOZEBOOM DIAGRAM
Gibbs-Roozeboom Diagram
An equilateral triangle representing a ternary system at constant temperature and pressure
Gibbs-Roozeboom Diagram
The components are in pure state at the apices:
Apex A:Component A is pure
Apex B:Component B is pure
Apex C:Component C is pure
Gibbs-Roozeboom Diagram
The Binary systems (only 2 components as the third component is absent) are illustrated at the edges of the triangle.
i.e.
Edge A-B - mixture consists only of components A and B - %C=0, meaning C is absent
Edge A-B
Gibbs-Roozeboom Diagram
Any point inside the triangle would mean a ternary system of composition XA, XB and XC
XA + XB + XC = 1
XA = %A/100
XB = %B/100
XC = %C/100
Other important parts of the diagram
Binodal CurveThe area below such curve represents a
region of immiscibility ○ Region where which a system will not exist as
a homogeneous mixture.
Tie LineA line with which its endpoints determine the
composition of the two phasesdetermined experimentally and drawn within
the binodal curve
Other important parts of the diagram
Delta pointServes as a guide for finding the plait point
Plait PointIn this point, the two phases will have
identical compositionsUsually not located on the maximum of the
binodal curve○ The tie lines are not horizontal
A sample Gibbs-Roozeboom diagram
Plait Point
Binodal Curve
Tie lines
Delta point
MATERIALS
Apparatus
Separatory funnels Erlenmeyer Flasks Burets and Buret holders Beakers
Reagents
H2O
CHCl3 CH3COOH NaOH KHP phenolphthalein
PROCEDURE
Construction of the binodal curve for the H2O-CHCl3-CH3COOH System
Method used: Turbidimetric methodSample is titrated until the first sign of
turbidity or cloudiness is observed○ Scattering of light by the very small droplets of
a second phase that forms upon titration of sufficient amounts and shaking results to the cloudiness of the mixture
Construction of the binodal curve for the H2O-CHCl3-CH3COOH System
Solutions of CH3COOH and H2O at different concentrations of 15, 30, 45, 60 and 70 %
(v/v) were subjected to turbidimetric analysis using CHCl3 as titrant
The % composition by weight was
determined for each mixture after turbidimetry
Points were plotted on
the diagram
Construction of the binodal curve for the H2O-CHCl3-CH3COOH System
Solutions of CH3COOH and CHCl3 at different
concentrations of 15, 30, 45, 60 and 70 % (v/v) with
respect to CH3COOH were subjected to
turbidimetric analysis,this time using H2O as titrant.
The % composition by
weight was determined for each mixture
after turbidimetry
Points were plotted on the
diagram as well.
Construction of Tie Lines
Four 100g g mixtures containing the H2O-CHCl3-CH3COOH were prepared
such that there will be approximately equal volumes
of conjugate phases.
Each was equilibrated in a 250-mL separatory funnel at
25 °C.
The conjugate phases were separated and transferred into 125-mL Erlenmeyer flasks, properly labeled.
The density of each phase was measured using a
pycnometer.
5.0 mL aliquots of each conjugate phase was titrated with 1.0M NaOH, previously standardized with KHP, up to
the phenolphthalein end point.
The values of the %w/w CH3COOH were located on
the binodal curve of the diagram for each conjugate
phase.
Drawing a straight line along the two points corresponding
to each prepared sample gave the tie lines
Determination of delta and plait points
Each tie line was extended until
the tie lines intercept at a certain point
The point of intersection
gave the delta point
A tangential line was drawn along the binodal curve, starting from the
delta point
The point where the binodal curve
and the tangential line meet gives the
plait point
RESULTS AND DISCUSSION
Titration of A-B with C
Solution number
%A(v/v)
vol A, ml
mass A, g
vol B, ml
mass B, g
vol C, ml
mass C, g
total mass, g
%(w/w)A %(w/w)B %(w/w)C
total %(w/w)
1 15 3.75 3.94 0.2 0.20 21.25 31.32 35.46 11.10 0.56 88.33 100.00
2 30 7.50 7.88 0.4 0.40 17.50 25.80 34.07 23.11 1.17 75.71 100.00
3 45 11.25 11.81 2.2 2.19 13.75 20.27 34.27 34.47 6.40 59.13 100.00
4 60 15.00 15.75 5.4 5.38 10.00 14.74 35.87 43.90 15.01 41.09 100.00
5 75 17.50 18.38 8.4 8.38 7.50 11.06 37.81 48.60 22.15 29.24 100.00
where: A=CH3COOH, B=H2O, C=CHCL3
Titration of A-C with B
Solutionnumber
%A(v/v)vol A,
mlmass A,
gvol B,
mlmass B,
gvol C,
mlmass C,
gtotal
mass, g%(w/w)
A%(w/w)
B%(w/w)
Ctotal %
1 15 3.75 3.94 21.25 21.19 0.8 1.18 26.30 14.97 80.55 4.48 100.00
2 30 7.50 7.88 17.50 17.45 1.0 1.47 26.80 29.39 65.11 5.50 100.00
3 45 11.25 11.81 13.75 13.71 1.6 2.36 27.88 42.37 49.17 8.46 100.00
4 60 15.00 15.75 10.00 9.97 4.2 6.19 31.91 49.36 31.24 19.40 100.00
5 75 17.50 18.38 7.50 7.48 10.4 15.33 41.18 44.62 18.16 37.22 100.00
where: A=CH3COOH, B=H2O, C=CHCl3
Computed data for the Construction of the Binodal Curve
Sample Layer Volume A, ml vol B, ml vol C, ml
mass pycnome
ter, g
mass pycnometer +soln,
g
mass soln, g
mass pycnometer+wate
r, g
mass water, g
ρwater, g/mol
ρsoln, g/mol
P1upper 9.52 35.15 37.31 16.461 27.046 10.585 26.768 10.307 0.99704 1.023932
lower 9.52 35.15 37.31 16.461 31.425 14.964 26.768 10.307 0.99704 1.447531
P2upper 14.29 30.13 37.31 16.15 26.8 10.65 26.398 10.248 0.99704 1.036151
lower 14.29 30.13 37.31 16.15 30.834 14.684 26.398 10.248 0.99704 1.428624
P3upper 19.05 25.11 37.31 15.788 26.342 10.554 26.338 10.55 0.99704 0.997418
lower 19.05 25.11 37.31 16.616 31.171 14.555 26.906 10.29 0.99704 1.410293
P4upper 23.81 20.09 37.31 16.616 28.44 11.824 26.906 10.29 0.99704 1.145676
lower 23.81 20.09 37.31 15.788 30.39 14.602 26.338 10.55 0.99704 1.379979
Determination of the Delta and Plait points
Sample Layer Volume of aliquot, mL
ρsoln, g/ml mass of aliquot, g
NaOH concentration, mol/L
volume of NaOH
used, ml
MM A, g/mol mass A, g %(w/w)A
P1upper 5 1.023932 5.119661 0.9613 17.9 60.052 1.033331 20.1836
lower 5 1.447531 7.237657 0.9613 4.65 60.052 0.268435 3.7089
P2upper 5 1.036151 5.180755 0.9613 22.3 60.052 1.287334 24.8484
lower 5 1.428624 7.143118 0.9613 7.9 60.052 0.456051 6.3845
P3upper 5 0.997418 4.98709 0.9613 26 60.052 1.500928 30.0963
lower 5 1.410293 7.051466 0.9613 11.4 60.052 0.658099 9.3328
P4upper 5 1.145676 5.728378 0.9613 34.6 60.052 1.997388 34.8683
lower 5 1.379979 6.899895 0.9613 16.6 60.052 0.958285 13.8884
Sample Calculations
Construction of the Binodal Curve
,
(1.05 / )(3.75 ) 3.9375 3.94
A A A used
A
m V
m g mL mL g g
%( / ) 100%
3.94%( / ) 100% 11.10%
3.94 0.20 31.32
AA
A B C
A
mw w
m m m
gw w
g g g
Sample Calculations
Construction of the Tie Lines2 2
2
2
,
, ,
26.768 16.461 10.307
27.046 16.461 10.585
10.5850.99704 /
H O pycnometer H O pycnometer empty
H O
solution lower pycnometer solution pycnometer empty
solutionsolution water
H O
m m m
m g g g
m m m g g g
m gg mL
m
3, ,
1.023932 /10.307
5 1.023932 / 5.119661
117.9 0.9613 60.052 1.033331
1000
1.03%( / ) 100%
aliquot aliquot solution
A NaOH used NaOH M CH COOH
A
AA
aliquot
g mLg
m V mL g mL g
m V C M
mol g Lm mL g
L mol mL
mw w
m
3331
100% 20.1836%5.119661
g
g
Resulting Gibbs-Roozeboom Diagram
where: A=CH3COOHB=H2OC=CHCl3
Resulting Gibbs-Roozeboom Diagram
Delta point
Tie Lines
Plait point (P)Tangential line
Point b1 Point b2
Arc b1-P – CHCl3-rich phase
Arc P-b2 – H2O-rich phase
Overall Inferences
CH3COOH-H2O; CH3COOH-CHCl3Miscible; CH3COOH exhibits hydrogen
bonding with water and London interaction with CHCl3
H2O-CHCl3Only partially miscible; the two compounds
are of opposing polarities, hence the great tendency to form two phases, especially between points b1 and b2.
Applications
Mining, geological, pharmaceutical, metallurgical and agricultural studies and industries
Ex.metallic alloys, such as stainless steel (metallurgy); Shephard’s diagram (agriculture and geology)
Applications
Applications
Notes The last two Gibbs-Roozeboom Diagrams were
pre-made diagrams print-screened from the Ternary diagram plotter of the Chemix School software – Trial version: (URL: http://www.chemix-chemistry-software.com/chemistry-software.html).
The rest of the ternary diagrams were drawn using the Ternary diagram plotter of the Chemix School software and print-screened to prevent the inclusion of the software name in the presentation, a potential eyesore when presented. :P
REFERENCES
Alberty, R.A. and R.J. Silbey. 2001. Physical Chemistry. 3rd ed. MA, USA: John Wiley and Sons, Inc. p. 159.
Tamayo, J.P. 2008. CHEM 112: Physical Chemistry II Lecture Notes. UPLB:Institute of Chemistry. p. 64-66.
END